The raid itself was not destroyed. You don't have to rebuild that. This was a filesystem reformat (disk utility). So the RAID is happy (or should be except that he power cycled it without warning).

So the main issue is superblocks.
In the olden days, we could find a "good" superblock and run mkfs is a recovery mode pointing to that block. It would layout the filesystem again without touching the data itself. Then you could fsck or whatever.